1. Field of the Invention
The present invention relates to an information processing system that processes various types of data.
2. Description of the Related Art
In an information processing system such as a digital copier and an MFP that processes, for example, image data, a Peripheral Component Interconnect (PCI) bus is employed as an interface between devices. However, due to racing, skew, etc., a parallel PCI bus cannot provide a high data transfer rate sufficient for use in an image-forming device required to operate at a high speed and also to produce high quality images.
High-speed serial interfaces such as Institute of Electrical and Electronics Engineers (IEEE) 1394 interface and Universal Serial Bus (USB) are now studied to be used instead of the parallel PCI bus. For example, Japanese Patent Application Laid-Open No. 2001-016382 has proposed a technique using a high-speed serial interface such as the IEEE 1394 interface or the USB as an internal interface.
As another high-speed serial interface, the PCI EXPRESS (trademark), which is a successive version of the PCI bus, has been proposed and is now available for the practical use. Reference may be had to, for example, an article by Hisashi Satomi “An Overview of the PCI EXPRESS standard”, taken from journal “Interface”, July 2003. The PCI EXPRESS is a data communication network with a tree structure, including a root complex, switch, and the like.
Japanese Patent Application Laid-Open No. 2001-016382, however, does not refer to problems in simultaneous transmission of a plurality of image data sets. Besides, although the technique allows establishing a serial system with a high degree of freedom, in which a plurality of traffic flows occurs, the effects of restrictions on line synchronous transfer timing, etc. are not considered.